1. Field of the Invention
This invention relates to gardening tools, and in particular to a lawn rake with a debris collection means, to facilitate the collecting and holding of, for instance, leaves or cut grass.
2. Description of the Prior Art
A variety of lawn rakes and similar tools, having bundling capacity, are known. Different designs of lever systems are used, for example in U.S. Pat. No. 5,058,370 (Russell), U.S. Pat. No. 4,545,189 (Nelson), U.S. Pat. No. 2,797,544 (Fite), U.S. Pat. No. 2,504,943 (Zifferer), U.S. Pat. No. 2,891,374 (Richmond), U.S. Pat. No. 2,908,131 (Ross), U.S. Pat. No. 5,058,370 (Russell), U.S. Pat. No. 2,790,296 (Bernstein) and U.S. Pat. No. 5,303,536 (Tolliver). All these designs share the drawback of being relatively heavy to operate, i.e. the lever action upon the bundling element is heavy and requires the user of the garden tool to exert an unnecessarily high force on the lever system, to accomplish the bundling action. A further design of a garden tool, solely used for picking up already raked leaf piles, is described in U.S. Pat. No. 4,848,074 and U.S. Pat. No. RE 33,702 (Allen). The head of the device has a plurality of tines, pivotably connected to a base portion of the head and interconnected so that if one tine is pivoted, all the others follow the motion. The tines are arranged in a circular manner around a hollow handle. A cable, which runs inside the handle and is attached to a manipulating lever on the handle at one end, and attached to one of the tines at the other end, is used to uniformly move the tines inwardly in unison when the lever pulls the cable. The circular arrangement of the tines makes it extremely difficult to actually use this garden tool as a rake, it is suited primarily for bundling and picking-up leaves.
In the majority, there are three significant methods in the design of debris collecting rakes and rake like devices; U.S. Pat. No. 2,504,943, to Zifferer, is typical of the radial pivot to clutch method, whereas U.S. Pat. No. 2,790,296, to Bernstein is typical of the transverse pivot to clutch method.
The transverse method being an attempt to remove the need for a second articulating rake head which is commonly both heavy and difficult to position, whereas the radial method by reason of expectation may have greater capacity.
The third method being the circumferential clutch method described in U.S. Pat. No. Re.33,702, to Allen.
The aforementioned difficulty in applying force to an articulating rake head using levers, necessitates a combination of linkages and fulcrums of greater mechanical advantage than can be applied to a standard hand rake, to apply sufficient force and control to achieve the desired degree of utility. A combination of linkages for articulating a rake head is disclosed in U.S. Pat. No. 4,545,189 to Nelson, whereby the force is applied using a long thin rod placed in the harder to control centre of compression stress, rather than in the more preferential form of tension. The rod is acting on a lever of the third order at an angle that would apply negligible force to the distal end of the rake head during the last quadrant of rotation where it is most needed to clutch the debris. The method of using an additional lever of the second order to increase the mechanical advantage often seemingly fails to provide a product that gains the consumer's satisfaction.
In U.S. Pat. No. 2,797,544 to Fite and U.S. Pat. No. 2,891,374 to Richmond, both describe attempts to hide the large lever in a through the handle mount which may weaken the handle's resistance to stress beyond a reliable point.
U.S. Pat. No. 2,504,943 to Zifferer, describes a light weight grapple, in the form of an arcuate brace as sufficient means to grasp laminated debris, whereas the majority of prior art describe heavy debris collecting rakes, which suffer from ergonomic and mechanical limitations. The resulting force at the grapple is not constant and almost nullified during the last quadrant of rotation where the greatest amount of force is needed and whereby friction, return springs and massive components have consumed the majority of the applied force, making rakes and rake like devices of this type heavy and unwieldy.